A. field of the Invention PA1 B. description of the Prior Art
The device of the present invention relates to a new and improved wafer switch that may be adjusted independent of a printed circuit board included in the switch and of the position of an operating shaft, and to a new and improved method for continuous adjustment of a multiple position wafer switch relative to a printed circuit board and operating shaft.
In switching arrangements wherein a multiple position wafer switch is employed, preliminary adjustment of the switch blade prior to installation is difficult; particularly in close quarters such as a tuner of a television.
Typically, in a television tuner, the wafer switch includes a printed circuit board such that its switch or wiper blade abuts one or more contacts etched upon the board. In addition, the wafer switch is connected or secured to the shaft of the television tuner knob and must rotate with the tuner knob so the wiper blade will abut the appropriate contact. A digital output instrument is electrically connected to the circuit board and records the position of the blade and thus the channel to which the tuner is turned.
In this environment, the wafer switch may not be preadjusted relative to the tuner knob and requires adjustment after installation on the tuner shaft.
Another problem with the typical prior art wafer switch is that during rotation the wiper blade drops between contacts onto the insulating circuit board whereupon the abrasive action of the board on the wiper produces excessive wear. The wiper material may also smear across the board surface into the gap between contacts thereby shorting adjacent contacts and resulting in switch failure.
A further problem with prior art wafer switches is their inability to have continuous adjustment as opposed to incremental ratchet type adjustment in positioning the wiper blades on the appropriate contact. This results in significant problems in small enclosures where adjustment is difficult.